Compositions of matter having anti-rust properties



United States Patent 3,121,059 COMPOSITIONS 0F MATTER HAVING ANT I-RUST PROPERTIES Edwin L. De Young, Chicago, 11]., and Roger W. Watson, Highland, Ind, assignors to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed Dec. 5, 1960, Ser. No. 73,530 5 Claims. (Cl. 252-425) This invention relates to novel rust inhibited normally liquid oil compositions and especially petroleum products wherein the composition is in the presence of a rust producing amount of water. More particularly, this invention relates to novel rust inhibitors and their inclusion in normally liquid oils in contact with rust producing water for inhibiting the rusting of ferrous metal in contact with the oil.

The rusting of steel and other ferrous metals used in the transportation and storage of petroleum produc s has always presented a serious problem in the petroleum industry. The rusting of pipelines and tanks used to transport normally liquid oil products represents in itself a substantial annual economic loss in maintenance and re placement costs. 'In addition, the presence of sediment and rust as a result of the rusting action of water and carryover of such sediment and rust into fuel burning insulations creates fuel quality and operating problems. Such sediment and rust also creates special problems in the case of aviation gasoline where the hazard of engine stoppage through clogging of filters and carburetion equipment presents special hazards. The rusting problem also applies to the handling and use of motor and diesel fuels as well. A particular problem is created by rust formation in lubricating oils such as engine lubricating oils where, during normal lubrication operations, rusting of ferrous metal parts and the presence of resulting rust particles may create uneven contact of moving metal parts with resulting increased friction. In such lubricating operations, surface wear of moving parts is greatly increased.

Further, the rusting of fuel storage tanks used to supply industrial and household burner installations and the rusting of lubricating oil storage tanks used to supply industrial machinery present serious problems. Although the rusting of such storage tanks may cause eventual breakthrough of storage tank Walls and result in losses arising from the necessary replacement of storage tanks, the greater problem results from the accumulation of rust in petroleum products and particularly in normally liquid oils and the future use of such oils and products. Thus, clogging of filters, burners, feed lines, etc., as well as undue wear in industrial machinery and internal combustion engines with ultimate destruction of such machinery or engines and their intended use may result.

The problem of rusting is associated with the presence of moisture, i.e., Water, in the oil products by entrainment, condensation, and solution. In most cases, the problem is accentuated by the presence of a separate water phase. Thus, in the storage and bulk shipment of products such as gasoline, it is common practice to maintain a water layer as tank bottoms. Even Where a water layer is not used as tank bottoms, a separate water phase may form by continual or repeated condensation of moisture, associated with tank breathing or the alternate expansion and contraction of the bulk with temperature change unless special precautions are taken.

In the particular case of lubricating oils present in internal combustion engines, Water may also be accumulated by condensation from air admitted to the crankcase through crankcase breathing, and water may also be admitted into the crankcase by blow-by from the combustion chamber.

3,121,059 Patented Feb. 11, 1964 Too 4 Therefore, the problem of rust inhibition of oils in the presence of Water is a universal problem applicable to at least some extent to -a wide variety of petroleum oils. Thus, it becomes necessary to impart to such oils an ability to protect ferrous metals against rusting normally caused by the presence of Water. Many addition agents have been proposed for this purpose. It has been proposed to add to such oil products a rust inhibiting agent which is capable of protecting ferrous metal parts. Many such addition agents have been proposed. In the past, fatty acids have been widely used as rust inhibitors. However, fatty acids have a disadvantage in that they may become corrosive to certain non-ferrous metals. This problem is particularly acute in the case of internal combustion engine lubricating oils wherein operation is at high temperature and non-ferrous alloy bearings are present.

We have now provided rust inhibited oil compositions which protect against rusting of ferrous metals in the presence of normally rust producing amounts of water. The rust inhibiting addition agents of this invention do not contain free fatty acid groups and thereby overcome the difliculty encountered in the use of fatty acid rust inhibitors. Accordingly, our present invention provides a normally liquid oil, such as, for example, a petroleum oil, in the presence of water and containing a rust inhibiting minor amount of an oil-soluble molybdic acid complex of a triol monoester. The triol portion of the complex is an open chain hydrocarbon triol group having from 3 to 10 carbon atoms and the monoester group is an open chain hydrocarbon group having an ester linkage with the triol group. The open chain hydrocarbon portion of the monoester group may contain from 5 to 18 carbon atoms and preferably from 7 to 12 carbon atoms. The small amount of molybdic acid complex of the triol monoester contained in the present compositions is an amount suiiicient to inhibit rusting normally caused by the water.

Although greater or lesser amounts of the molybdic acid complex of the triol monoester, referred to hereinafter as the triol monoestermolybdic acid complex, may be used in the composition of this invention, it is advantageous to use from about 0.001 to about 10 weight percent of the complex based on the normally liquid oil. The preferred range of concentration based on oil is from about 0.001 to about 2.0 weight percent of the complex. Of course, the amounts may be varied as desired and as required for a particular use in rust inhibition. For example, if it is anticipated that the oil product will come into contact With or accumulate greater amounts of water, more of the complex may advantageous be included therein.

The complex of this invention is conveniently formed by the reaction of approximately equimolar amounts of a triol monoester with molybdic acid. The reaction temperature may be any temperature in the range of from about to about 160 C. It has been found that the reaction proceeds more readily at temperatures above about F. and such temperatures are preferred. It is also preferred to carry out the reaction at a temperature below the boiling point of the triol monoester in order to eliminate the necessity for pressurizing the reaction mixture to keep the triol monoester from distilling off. The reaction may conveniently be carried out at the reflux temperature of the reaction mixture using an overhead condenser to condense and return triol monoester to the reaction mixture. Also, the reaction may conveniently be carried out in the presence of an inert solvent such as xylene, benzene, toluene and the like at the reflux temperature of the solvent.

The reaction is carried out until more than one mole of water per mole of molybdic acid or per mole of triol monoester is produced as a reaction by-product. The water may conveniently be taken overhead, for example, through a condenser adjusted to return triol monoester or solvent to the reaction mixture, and may be collected and measured to determine the amount of water formed as a by-product. Other means such as liquid traps, for collecting and/or measuring water formed during the reaction, are well known to the art. Although the molybdic acid and triol monoester are reacted in approximately equimolar amounts, an excess of either reactant may be included in the reaction mixture. Thus, the moles of water are determined with reference to the moles of the reactant present in lesser amounts in the reaction mixture. The first mole of water formed as a reaction by-product indicates formation of an intermediate composition which is further reacted to form the complex of the present invention. The desired product is formed during the splitting out of a second mole of water and, therefore, after one mole of water has been formed as a by-product, formation of the desired complex commences.

The reaction time will depend upon the size of the reaction mass and is determinable for any combination of reactants, and any reaction mass by recovering and collecting water formed as a by-product as discussed above. As an example, it has been found that at about 150 C. the reaction is generally complete within about 4 hours.

As indicated above, although the reactant is between equimolar amounts of the molybdic acid and triol monoester, molar excesses of either reactant may be includ ed in the reaction mixture. It is not believed that an excess of either reactant in the product will adversely affect the product or the function of the product. However, any insoluble inorganic molybdenum compounds resulting from the inclusion of an excess of molybdic acid in the reaction mass may be removed, if desired, such as by filtering.

-It is preferred, for complete utilization of the reaction, that the reaction be carried out until about 2 moles of water are formed as a by-product for each mole of the reactant included in the lesser amount in the reaction mixture. The triol monoesters may conveniently be prepared by reacting equimolar amounts of a triol having 3 to 10 carbon atoms and a carboxylic acid having 5 to 18 carbon atoms and preferably 7 to 12 carbon atoms under known esterification conditions. The resulting triol monoester, used for complexing with molybdic acid in accordance herewith, therefore, contains from 3 to carbon atoms in the triol group and 5 to 18 carbon atoms in the monoester group. It is preferred that the triol group and/ or the monoester group be sufliciently straight chained to provide the characteristic of oil-solubility to the complex. Examples of typical triol monoesters useable in forming the complexes of this invention are glyceryl monocaprylate, glyceryl monooleate, glyceryl monohexadecanoate, glyceryl monocaprate, glyceryl monomyristate, glyceryl monopalmitate, glyceryl monopentanoate, 2,2-dimethylol-butyl caprylate, 2,2-diethylol-amyl laurate, 2,2-dimethylol-octyl oleate, 2,3-dimethylol-hexyl hexanoate, 1-methyl-5,5,dimethylol-hexyl decanoate, 2,2-dimethylol-propyl stearate, 2,2-dimethylolbutyl pentanoate, 2,2-dimethylol-butyl caproate, 2,2-dimethylol-butyl laurate, 9,10-dihydroxydecy1 oleate, 4,5- dihydroxy-hexyl laurate, 6-methylol-7-hydroxy-heptyl linoleate, 2,2-dimethylol heptyl stearate, etc.

The molybdic acid of the present complexes may be derived from the inclusion of any one or more of a variety of molybdic acid compounds in the reaction mixture. For example, molybdic acid may be added to the reaction mixture in the form of molybdic acid or molybdic hydroxide, molybdic anhydride, molybdenum oxides such as molybdenum trioxide and/ or molybdenum sesquioxide, molybdic acid salts such as ammonium molybdate and/or ammonium paramolybdate, halogencontaining molybdenum compounds such as molybdenum chloride, and the like.

The complexes of this invention are soluble in the 011 product in which they are included and, therefore, are defined as oil-soluble. Amounts exceeding the solubility of the complex in oil are neither necessary nor desired.

The splitting out of 2 moles of water as a by-product in formation of the complexes of this invention indicates salt formation. Thus, it is believed that at least some salts form during the reaction and, although the structure of the salts is unknown, it is believed that the complexes of the present invention include at least small amounts of compositions having the structural formula:

wherein R is an open chain (non-cyclic) hydrocarbon group having from 3 to about 10 carbon atoms and R is an open chain hydrocarbon group having from about 5 to about 18 carbon atoms and preferably from 7 to 12 carbon atoms.

The above formula may appear to be correct with reference to prior art theories such as that of Abbot et al., US. 2,795,552, patented June 11, 1957. However, we have been unable to substantiate the above formula of the complexes of this invention and it is not intended that this invention be limited to any theory concerning the structure of the complexes.

The normally liquid oils of the compositions of this invention are those normally liquid oils boiling in the gasoline through lubricating oil boiling range, and especially petroleum oil products boiling in that range. Broadly, such oils include gasoline, other hydrocarbon fuel oils, and lubricating oils. The oils may be gasoline blending stocks such as reformates and virgin and cracked naphthas or the oil may be a blended gasoline stock. The lighter oils useable include gasoline and the hydrocarbon fuel oils normally used in burner installations, diesel engines, as well as those used for insecticide carriers. For example, the oils of the composition of this invention may be residual or distillate fuel oil such as diesel fuel, jet fuel, heavy industrial residual fuel (e.g., Bunker C), furnace oil, heater oil fractions, kerosene, gas oil, etc. Of course, any mixtures of residual and/or distillate oils are also intended. The fuel oil may be a virgin or cracked petroleum distillate fuel oil and may advantageously boil in the range of from about 200 to about 750 F. Such fuel oils may contain or consist of cracked components, such as for example, those derived from cycle oils or cycle oil cuts boiling in the gasoline range or heavier and usually boiling in the range of from about 450 to about 750 F. Such cycle oils may be derived by catalytic or thermal cracking. High sulfur fuels and low sulfur fuels such as diesel oils and the like may also be used. The distillate fuel oil is preferably a hydrocarbon distillate fuel oil.

Also intended are the oils used for lubricating purposes and/or metal working purposes. Such oils include the cutting oils, drawing oils, grinding oils and other extreme pressure oils. Also intended are the glass grinding oils which are usually blends of kerosene containing dispersance addition agents. Other useable lubricating oils are those normally falling in the lubricating viscosity range. Such lubricating oils include the hydrocarbon or mineral lubricating oils of naphthenic and/or paratfinic types. Such lubricating oils may be derived by conventional methods such as solvent extraction and acid treatment. Synthetic oils may also be used. Such synthetic oils include the synthetic hydrocarbon oils of the alkylene polymer type, the alkylene oxide polymers and their derivatives such as propylene oxide polymers and esters thereof dicarboxylic ester synthetic oils including dibutyl adipate, diethyl hexyl sebacate, =fumarate polymers, di alkyl azelates, pelargonates, etc. Other synthetic lubricating oils which are useable are the alkyl benzene oils such as tetradecyl benzene. The non-hydrocarbon synthetic lubricating oils are also intended; such oils include the polysiloxanes such as polyalkyl, polyaryl, polyalkoxy, etc., siloxanes and the silicate ester oils such as the tetraalkyl silicates. The hydrocarbon oils are preferred.

As indicated above, other addition agents such as dispersancy agents and extreme pressure agents may be included in the liquid oil. Such other addition agents are used to perform particular functions. Thus, where desired, pour point depressants, corrosion inhibitors, combustion improvers, viscosity index improvers, oiliness agents, and the like may also be added.

The following examples illustrate the compositions of the present invention and are included for the purpose of illustration and description of the invention, and not for purpose of limitation of the scope of the invention.

Example I This example illustrates the preparation of a preferred triol monoester-molybdic acid complex for use herein. The complex of this example is a glyceryl monoestermolybdic acid complex. Accordingly, glyceryl monocaprylate, one of the reactants used in forming the complex, was prepared by reacting equimolar amounts of glycerol and octanoic acid in xylene at about 145-150 C. until one mole of water was taken overhead and collected per mole of glycerol or octanoic acid. The xylene solvent was then stripped off by heating. 327 grams (1.5 moles) of the resulting glyceryl monocaprylate and 265 grams (1.5 moles) of ammonium molybdate were mixed in 100 ml. of xylene solvent at 25 C. and heated under total reflux conditions (145 C. to 160 C.) for 4 hours. 47 ml. of water and 34 ml. of xylene were taken overhead and collected. Heating was continued for 75 minutes with no further removal of water. The reaction mixture was then cooled to about 25 C. and filtered through Celite.

Example II As another example of the preparation of a triol monoester molybdate, 406 grams (1.5 moles) of trimethylolpropane monocapry late, prepared in the same manner as the glyceryl monocaprylate of Example I except using trimethylolpropane in place of glycerol, were mixed with 265 grams (1.5 moles) of ammonium molybdate in 100 ml. of xylene solvent. The mixture was heated for about 4 hours at 145160 C. under reflux conditions and 39 ml. of water and 44 ml. of xylene were then taken overhead and collected. The reaction mixture was then cooled to about room temperature and filtered through Celite. The filtered product contained 13.3% molybdenum.

The addition agent of this invention was tested for its ability to aid in preventing the rusting of ferrous metal parts in the presence of water. Accordingly, tests were conducted in accordance with the ASTM-D-655 Rust Test. Briefly the test procedure involved stirring a mixture of 300 ml. of each sample listed below with 30 ml. of distilled water in a beaker at a temperature of about 140 F. with a cylindrical steel specimen completely immersed therein. The test was continued for a period of 24 hours. The samples tested were as follows:

Sample ABase oil containing 0.1 weight percent of the product of Example I.

Sample BBase oil 1 containing 0.001 weight percent of the product of Example I.

Sample C-Base oil containing 0.1 weight percent of the product of Example II.

Sample D--Base oil 1 containing 0.01 weight percent of the product of Example II.

Sample BBase oil 1 alone.

The base oil was a white refined mineral oil having a viscosity of 140445 sec. at C.

At the end of the 24-hour test period, the steel specimens were inspected for rust and rated as to the amount of rust present. A perfect rating indicates no rust prescut. The results were as follows:

Sample: Rating A Perfect.

B Perfect. C Moderate rusting. D Moderate rusting. E Severe rusting.

The above test results demonstrate the utility of the present rust inhibitors and also demonstrate the excellence of the preferred glyceryl monoester-molybdic acid complex in rust inhibiting activity.

It is evident from the foregoing that we have provided rust inhibited oil compositions containing the rust inhibitor described hereinabove.

We claim:

1. A rust inhibited oil composition comprising a major proportion of a normally liquid hydrocarbon oil and containing an efiective amount of an oil-soluble molybdic acid complex of a triol monoester wherein the triol group is an open chain hydrocarbon triol having from 3 to 10 carbon atoms and the monoester group is the remainder of an esterified open chain carboxy-lic acid having from 5 to 18 carbon atoms, said effective amount being sufiicient to inhibit rusting.

2. The composition of claim 1 wherein said hydrocarbon oil is a mineral lubricating oil.

3. A composition inhibited against causing rusting which comprises a hydrocarbon oil, and from about 0.01 to about 2.0 weight percent of a rust-inhibiting oil-soluble molybdic acid complex of alkanetriol monoester having from 3 to 10 carbon atoms in the alkanetriol group and from 5 to 18 carbon atoms in the monoester group.

4. The composition of claim 3 wherein said oil-soluble complex is the molybdic acid complex of the glycerol monoester of mixed faty acids.

5. The composition of claim 3 wherein said oil-soluble molybdate is the molybdic acid complex of the trimethylolpropane monoester of mixed fatty acids.

References Cited in the file of this patent UNITED STATES PATENTS 2,527,889 More at al. Oct. 31, 1950 2,560,202 Zimmer et al. July 10, 1951 2,795,550 Harle et al. June 11, 1957 2,795,552 Abbott et al. June 11, 1957 

1. A RUST INHIBITED OIL COMPRISING A MAJOR PROPORTION OF A NORMALLY LIQUID HYDROCARBON OIL AND CONTAINING AN EFFECTIVE AMOUNT OF AN OIL-SOLUBLE MOLYBDIC ACID COMPLEX OF A TROIL MONOESTER WHEREIN THE TRIOL GROUP IS AN OPEN CHAIN HYDROCARBON TRIOL HAVING FROM 3 TO 10 CARBON ATOMS AND THE MONOESTER GROUP IS THE REMAINDER OF AN ESTERIFIED OPEN CHAIN CARBOXYLIC ACID HAVING FROM 5 TO 18 CARBON ATOMS, SAID EFFECTIVE AMOUNT BEING SUFFICIENT TO INHIBIT RUSTING. 